Why do alkenes prefer to undergo electrophilec addition reaction while arenes prefer electrophilic substitution reactions ? Explain.

Explanation

Alkenes are rich source of loosely held pi `(pi)` electrons due to which they show electrophilic addition reaction . Electrophilic addition reaction of alkenes are accompanied by large energy changes so these are energetically favourable than of electrophilic substitution reactions. In special conitions alkenes also undergo free radical substitution reactions.

In arnes during electrophilic addition reactions, aromatic character of benzene ring is destroued while during electrophilic substitution reaction it remains intact. Electrophilic substItion reactions of arenes are energetically more favourable than that of electrophilic addition reaction.
That's why alkenens prefer to undergo electrophilic addition reaction while while arenes prefer electrophilic substitution reaction.